Method and electronic device for the pulsemodulated actuation of a load
Method and electronic device for the pulsemodulated actuation of a load in a vehicle, a period duration (TPM) of a frequency (fPM) of the pulse modulation being able to be divided into an integer number (N) of sections (TSTEP), the duration of each of which corresponds to a multiple of a period duration (TOSC) of a clock signal, and the method having the steps of: calculating a frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of a period of the pulse modulation on the basis of underlying frequency modulation, and determining the duration of a respective section (TSTEP) of a period duration (TPM) of the pulse modulation using the calculated frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of a period of the pulse modulation.
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This application claims the benefit of International application No. PCT/EP2016/061109, filed May 18, 2016, which claims priority to German application No. 10 2015 209 469.3, filed May 22, 2015, each of which is hereby incorporated by reference.
TECHNICAL FIELDThe technical field relates to a method and/or electronic device for the pulsemodulated actuation of a load in a vehicle.
BACKGROUNDPulsewidthmodulation (“PWM”) actuation is often used in electronic control units for an antilock braking system (“ABS”) and/or an electronic stability program (“ESP”) in order to implement digital/analog conversion, for example for actuating the valves, operating the pump, or brightnesscontrollable warning lamps. Such a method is described, for example, in German patent publication No. DE 10 2012 213 874 A1, in which an actual duty factor of the PWM is changed from a first duty factor to a second duty factor in order to limit peak currents and the maximum gradient of the current edges when actuating a pump motor. The PWM actuations are usually generated by integrated circuits (e.g., microcontroller and mixedsignal circuit). However, the disadvantage of the actuation with a pulsewidthmodulated signal may be that the frequent switchingon and switchingoff of the output driver stages results in increased electromagnetic radiation and/or disruption of the energy supply network in the vehicle. A selected fixed PWM frequency may also become noticeable as undesired noise in the vehicle. These disadvantages are partially compensated for using complicated techniques outside the integrated circuits, for example, stabilization circuits for the voltage supply at the level of the electronic control unit or noisesuppressing measures in the vehicle.
As such, it is desirable to present a costeffective but improved electromagnetic compatability, in particular emitted interference, and to reduce the emission of background noise. In addition, other desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
BRIEF SUMMARYA method for the pulsemodulated actuation of a load in a vehicle, according to one exemplary embodiment, is described herein. A period duration of a frequency of the pulse modulation is able to be divided into an integer number of sections. The duration of each section corresponds to a multiple of a period duration of a clock signal. The method includes calculating a frequency or period duration of a period of the pulse modulation on the basis of underlying frequency modulation. The method also includes determining the duration of a respective section of the period duration of the pulse modulation using the calculated frequency or period duration of a period of the pulse modulation.
It is therefore advantageously possible to implement frequency modulation, in particular for execution by a digital circuit inside a digital circuit or a mixedsignal circuit (e.g., hardware implementation), thus enabling costeffective production and resourcesaving operation. It is possible to generate frequencies, the sections of which cannot be generated by integer multiples of the clock signal, which enables frequency modulation which can be tuned in a comparatively fine manner. The frequency modulation advantageously makes it possible to distribute the interference energy to a wide frequency band, thus making it possible to improve the electromagnetic compatibility, in particular the emitted interference, and to reduce the emission of background noise of the underlying electronic device.
The clock signal may be a periodic clock signal which is generated by an oscillator, but may also be a clock signal derived therefrom, for example by frequency dividers. In this case, the pulsemodulated signal is used, in particular, to actuate an output stage which switches the load circuit(s) of the loads, as a result of which a mean current or a mean voltage is established according to the actuation. Depending on the implementation of the circuit, the actuation signal is “1” (pulse), for example, for a predefined number of sections and the actuation is “0” for the further course of the PWM period. The duration of a period of the pulse modulation is variable on account of the frequency modulation. Nevertheless, the predefined number of sections forming the pulse may preferably likewise be predefined, with the result that a temporal consistency of the pulse width over the frequency range of the frequency modulation or additional pulsewidth modulation for each actuation frequency can be achieved, for example. In this respect, according to the invention, this may be pulsefrequency modulation superimposed on the pulsewidth modulation, pure pulsefrequency modulation or pulsewidth modulation superimposed on the pulsefrequency modulation.
According to one preferred development of the method, the frequency or period duration of a period of the pulse modulation is calculated by means of a recursive calculation, a frequency or period duration of a preceding period of the pulse modulation being used. Multiplication and division can therefore be achieved in a parallel manner by means of additions and subtractions.
The frequency or period duration of a subsequent period of the pulse modulation is preferably calculated during an ongoing period of the pulse modulation. Alternatively, it is possible to calculate, for example, the frequency or period duration of an ongoing period of the pulse modulation during—in particular comparatively shortly after the beginning of—the ongoing period of the pulse modulation.
The frequency or period duration of a subsequent period of the pulse modulation is preferably calculated precisely once during an ongoing period of the pulse modulation. This advantageously makes it possible to calculate the frequency or period duration of the subsequent period in a more resourcesaving manner.
A remainder, which arises when calculating the frequency or period duration of the period of the pulse modulation, is preferably taken into account within a subsequent period of the pulse modulation. As a result, the error which is made when calculating the frequency or period duration of the subsequent period of the pulse modulation is taken into account.
The underlying frequency modulation preferably follows a predefined frequency change profile. This enables optimization with respect to the avoidance of particular frequencies for the purpose of reducing the emitted interference, for example. In this case, the frequency of the pulsemodulated signal is expediently varied between a minimum frequency and a maximum frequency.
The approximation that the frequencies of successive periods of the pulse modulation or the period durations of the pulse modulation are approximately the same is used to calculate the frequency or period duration of the period of the pulse modulation. An error which occurs as a result of the approximation can be advantageously disregarded for a multiplicity of applications.
The duration of the sections of a period of the pulse modulation is preferably iteratively determined separately for each section using the frequency or period duration of an ongoing period of the pulse modulation. This makes it possible to calculate the section durations with particularly little effort.
According to one development of the invention, the duration of a respective section of the period duration of the pulse modulation is also determined on the basis of a ratio value of the duration of a section to the period duration of the clock signal.
According to one preferred embodiment of the invention, the following steps are carried out in order to determine the duration of the sections of a period of the pulse modulation, where R_{STEP }represents a remainder value, f_{OSC }represents a frequency of the clock signal, N represents the number of sections and f_{PWM }represents the frequency of a period of the pulse modulation:
 1. Initializing the remainder with a value equal to zero at the beginning of a period of the pulse modulation,
 2. Performing an allocation:
at the start of a section,
 3. Performing an allocation:
after a period of the clock signal, and
 4. Terminating the section and performing the second step if the remainder is less than the frequency of the period of the pulse modulation, and otherwise repeating the third step.
During the calculations or allocations, additional parameters and/or constants may possibly be taken into account and/or the calculations as such—given substantially the same result—can be carried out in an alternative manner.
The number of sections within a period of the pulse modulation is preferably selected as a power of two, the exponent being an integer. As a result, a division by N (see second step) corresponds to a shift operation by the number of digits stated in the exponent, thus enabling a resourcesaving calculation, even for an implementation in hardware. The expression f_{OSC}/N (second step) is expediently constant within an actuation.
The invention also describes an electronic device for the pulsemodulated actuation of a load in a vehicle, which device has at least one circuit for generating a pulsemodulated signal, which circuit can be operated using a clock signal, a period duration of the pulsemodulated signal being able to be divided into an integer number of sections, the duration of each of which corresponds to a multiple of a period duration of the clock signal, the device also being distinguished by the fact that the circuit is configured to generate a pulsemodulated signal of different period durations or frequencies, the pulsemodulated signal being able to have, within a period duration, a noninteger mean value of ratio values of the duration of the sections of a period of the pulse modulation to the period duration of the clock signal. The next pulse modulation frequency to be actuated is therefore calculated with little circuitry.
According to one advantageous development, the circuit is configured to generate sections of different time periods within a period duration of the pulsemodulated signal.
The electronic device is preferably configured in such a manner that it can execute or executes the method according to the invention.
Substantially the same advantages as those already described for the method according to the invention apply to the device according to the invention.
Further embodiments emerge from the following description of exemplary embodiments on the basis of figures, in which:
and
Depending on a mean current to be set for the purpose of actuating a load, the actuation signal is “1” for a particular number of sections within the PWM period and the actuation is “0” for the further course of the PWM period. This PWM signal can be used to switch a pump driver, for example, on and off.
The section width T_{STEP }within a PWM period is constant in this case. Therefore, particular discrete period durations T_{PWM }result on the basis of the base clock with the step width T_{OSC}:
T_{PWM}=T_{STEP}·N=T_{OSC}·V_{PWM}·N
where the values of V_{PWM }and N are integers.
This constitutes a considerable restriction, in particular in mixedsignal circuits, since the oscillator frequency with the period duration T_{OSC }cannot be stipulated in an arbitrary manner in these cases. If, for example, an oscillator frequency of 50 MHz and N=1024 are chosen, only the discrete frequencies:

 f_{PWM1}=48.8 kHz
 f_{PWM2}=24.4 kHz
 f_{PWM3}=16.3 kHz
 f_{PWM4}=12.2 kHz
 . . .
can be achieved.
It is explained below how, starting from the frequency profile according to
The following values are given for the calculation:

 f_{PM}=1/T_{PM }Desired center frequency of the PM actuation
 f_{MIN}=1/T_{MIN }Minimum PM actuation frequency
 f_{MAX}=1/T_{MAX }Maximum PM actuation frequency
 f_{FM}=1/T_{FM }Modulation frequency
 f_{OSC}=1/T_{OSC }Base clock of the digital circuit
The frequency profile according to
The calculation of the frequency for any desired times t is not absolutely necessary inside a digital circuit for PM actuation since, in particular, the distance between two successive rising signal edges is relevant as the period duration T_{PM}. It therefore generally suffices to calculate the PM frequency with the period duration T_{PM }once for each PM period. A recursive method which is explained on the basis of
The sign ± in this case respectively distinguishes whether there is a rising or falling edge of the PM frequency. The step widths df and dT change with the PM frequency result from the PM period duration, which changes with the PM frequency.
In order to determine the frequency f_{PM+1}, a calculation of the following form is carried out:
There are countless ways of calculating the term
In this case, the exemplary embodiment corresponding to
In the calculation example according to
The following method steps may be carried out:
 1. A value Erg is initialized with 0, a step counter is likewise set to 0 and a maximum value (>=n_{b}−n_{c}) which specifies the computation accuracy is stipulated for the step counter.
 2. If the first n_{c }bits of the variable b are greater than or equal to the value of c, c is subtracted from the first n_{c }bits of b. At the same time, a is added to the value Erg. If the first n_{c }bits of b are less than c, this step is skipped and step 3 is carried out.
 3. The step counter is incremented by 1. If the step counter has not reached the maximum value, b and Erg are shifted one bit to the left and the method jumps to step 2. If the counter has reached the maximum value, the computation operation is terminated.
Erg now represents the result of the computation operation involving multiplication and division. This calculation is carried out in each PM period in order to determine the PM frequency f_{PM+1 }of the next PM period. A division remainder R often occurs during this operation and is preferably taken into account in the next iteration step or when calculating the PM frequency of the PM period which follows the next PM period:
In this case, f_{PM−1 }represents the PM frequency of the preceding PM period, f_{PM }represents the PM frequency of the current PM period and f_{PM+1 }represents the PM frequency of the next PM period. However, this would require an additional division operation and a plurality of additional subtraction and shift operations. For further simplification when calculating the next PM frequency, it is assumed that two successive PM periods are very similar, with the result that: f_{PM−1}≈f_{PM}.
The following is obtained:
The divisor V_{PM+1 }of the subsequent PM period can be determined from the frequency f_{PM+1 }calculated using equation 1:
The value V_{PM+1 }is generally not an integer. As already explained for
In digital circuits, the number N of steps with the period duration T_{STEP }within a PM period is preferably selected as a power of two, that is to say N=2^{M}, where M is an integer. As a result, the division by N corresponds to a shift operation by M digits. The expression f_{OSC}/N is expediently constant within PM actuation, thus making it possible to achieve a particularly resourceefficient calculation.
The actual time period T_{STEP }of the sections of a PM period or the number of base clock periods T_{OSC }of the respective section is iteratively determined using the following algorithm:
 1. A remainder R_{STEP }is initialized with 0 at the beginning of a pulse modulation period.
 2. At the start of a section of the length T_{STEP}, the following allocation:
is carried out, where
and f_{PM }and V_{PM }represent the values f_{PM+1 }and V_{PM+1 }determined in the preceding PM period using equation 1.
 3. After a base clock period T_{OSC}, the following allocation
is carried out.
 4. If the remainder R_{STEP }is less than f_{PM}, the step T_{STEP }is finished and the method jumps to 2 in order to determine the length of the next step, otherwise 3 is repeated.
The frequency f_{PM+1 }of the next period of the pulse modulation can therefore be recursively determined using the parameters f_{OSC}/N, f_{MIN}, f_{MAX}, f_{FM}, and f_{PM}, in which case f_{OSC}/N, f_{MIN}, f_{MAX}, and f_{FM}, in particular, can also remain constant over a multiplicity of periods of the pulse modulation.

 f_{OSC}=6.656 MHz
 N=2^{8}=256
 f_{PM}=10 kHz
These input variables result in divisors V_{PM }of 2.6.
A remainder R_{STEP }is retained from step to step and makes it possible to achieve the desired value of V_{PM}=2.6 on average.
According to
Estimation of the Maximum Total Error of Half a PM Period
The simplification f_{PM−1}≈f_{PM }results in an error F which can occur during each iterative computation step:
Within half a PM period, the errors F of a PM period are added to form a total error F_{G }of half a PM period:
The maximum total error F_{MAX }of half a PM period can be estimated by:
This estimation is composed of three considerations, in particular:

 Remainder R can never become greater than the current frequency f_{PM}. If the remainder R is replaced with the maximum frequency f_{MAX}, an estimation is carried out according to the above.
 The error becomes maximal, the smaller the denominator becomes, and the frequencies f_{PM−1 }and f_{PM }are therefore each replaced with f_{MIN}.
 The iteration formula results in a sum of the enumerators in the form: f_{1}−f_{2}+f_{2}−f_{3}+f_{3}−f_{4 }. . . =f_{MAX}−f_{MIN}.
If an estimation in % is required, it is also possible to divide by the minimum PM frequency f_{MIN }to give the following:
For exemplary frequency modulations, the following results arise for the maximum total error of half a PM period:
In order to minimize the error, the extreme points f_{MIN }and f_{MAX }are preferably used as supporting points at which the recursive calculation is restarted by setting f_{MAX}=f_{PM }and f_{MIN}=f_{PM }in order to calculate f_{PM+1 }if the PM frequency is exceeded or is the same.
Claims
1. A method for the pulsemodulated actuation of a load in a vehicle, a period duration (TPM) or a frequency (fPM) of the pulse modulation being able to be divided into an integer number (N) of sections (TSTEP), the duration of each of which corresponds to a multiple of a period duration (TOSC) of a clock signal, wherein the method comprises: R STEP = R STEP + f OSC N  f PWM at the start of a section;
 calculating a frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of a period of the pulse modulation on the basis of underlying frequency modulation; and
 determining the duration of a respective section (TSTEP) of a period duration (TPM) of the pulse modulation using the calculated frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of a period of the pulse modulation;
 wherein the following steps are carried out in order to determine the duration (TSTEP) of the sections of a period of the pulse modulation, where RSTEP represents a remainder value, fOSC represents a frequency of the clock signal, N represents the number of sections and fPM represents the frequency of the pulse modulation: 1. Initializing the remainder (RSTEP) with a value equal to zero at the beginning of a period of the pulse modulation; 2. Performing an allocation:
 3. Performing an allocation: RSTEP=RSTEP−fPM after a period of the clock signal; and 4. Terminating the section and performing the second step if the remainder (RSTEP) is less than the frequency of the period of the pulse modulation (fPM), and otherwise repeating the third step.
2. The method as claimed in claim 1, wherein the frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of a period of the pulse modulation is calculated by means of a recursive calculation, a frequency (fPM−1) or period duration (TPM−1) of a preceding period of the pulse modulation being used.
3. The method as claimed in claim 1, wherein the frequency (fPM+1) or period duration (TPM+1) of a subsequent period of the pulse modulation is calculated during an ongoing period of the pulse modulation.
4. The method as claimed in claim 1, wherein the frequency (fPM+1) or period duration (TPM+1) of the subsequent period of the pulse modulation is calculated precisely once during an ongoing period of the pulse modulation.
5. The method as claimed in claim 1, wherein the underlying frequency modulation follows a predefined frequency change profile.
6. The method as claimed in claim 1, wherein an approximation that the frequencies (fPM+1, fPM) of successive periods of the pulse modulation or the period durations (TPM+1, TPM) of the pulse modulation are approximately the same is used to calculate the frequency (fPM+1, fPM) or period duration (TPM+1, TPM) of the period of the pulse modulation.
7. The method as claimed in claim 1, wherein the duration (TSTEP) of the sections of a period of the pulse modulation is iteratively determined separately for each section using the frequency (fPM) or period duration (TPM) of an ongoing period of the pulse modulation.
8. The method as claimed in claim 7, wherein the duration (TSTEP) of a respective section of the period duration (TPM) of the pulse modulation is also determined on the basis of a ratio value (VPM) of the duration of a section (TSTEP) to the period duration (TOSC) of the clock signal.
9. An electronic device for the pulsemodulated actuation of a load in a vehicle, comprising: R STEP = R STEP + f OSC N  f PRM at the start of a section;
 at least one circuit for generating a pulsemodulated signal, said circuit may be operated using a clock signal, a period duration (TPM) of the pulsemodulated signal being able to be divided into an integer number (N) of sections (TSTEP), the duration of each of which corresponds to a multiple of a period duration (TOSC) of the clock signal;
 said at least one circuit configured to generate a pulsemodulated signal of different period durations (TPM) or frequencies (fPM+1, fPM), the pulsemodulated signal being able to have, within a period duration (TPM), a noninteger mean value of ratio values (VPM) of the duration of the sections (TSTEP) of a period of the pulse modulation to the period duration (TOSC) of the clock signal;
 wherein the following steps are carried out by at least one circuit in order to determine the duration (TSTEP) of the sections of a period of the pulse modulation, where RSTEP represents a remainder value, fOSC represents a frequency of the clock signal, N represents the number of sections and fPM represents the frequency of the pulse modulation: 1. Initializing the remainder (RSTEP) with a value equal to zero at the beginning of a period of the pulse modulation; 2. Performing an allocation:
 3. Performing an allocation: RSTEP=RSTEP−fPM after a period of the clock signal; and 4. Terminating the section and performing the second step if the remainder (RSTEP) is less than the frequency of the period of the pulse modulation (fPM), and otherwise repeating the third step.
10. The electronic device as claimed in claim 9, wherein said at least one circuit is configured to generate sections of different time periods (TSTEP) within a period duration (TPM) of the pulsemodulated signal.
20080157894  July 3, 2008  Hariton et al. 
20090067487  March 12, 2009  Diewald 
20100049470  February 25, 2010  Szajnowski 
20100090775  April 15, 2010  Huda et al. 
20110261875  October 27, 2011  Alexander et al. 
20130015798  January 17, 2013  Wright 
101517897  August 2009  CN 
102007043340  March 2009  DE 
2008095145  August 2008  WO 
2014178673  November 2014  WO 
 Korean Office Action dated Dec. 20, 2018 for corresponding Korean Patent Application No. 1020177033719.
 International Search Report and Written Opinion dated Sep. 1, 2016 from corresponding International Patent Application No. PCT/EP2016/061109.
 German Search Report dated Apr. 5, 2016 for corresponding German Patent Application No. 10 2015 209 469.3.
 Chinese Office Action dated Aug. 4, 2020 for the counterpart Chinese Patent Application No. 20168002945732.
 Chinese Notice of Allowance dated Mar. 4, 2021 for the counterpart Chinese Patent Application No. 20168002945732.
Type: Grant
Filed: Nov 8, 2017
Date of Patent: Feb 14, 2023
Patent Publication Number: 20180069539
Assignee: Continental Teves AG & Co. OHG (Frankfurt am Main)
Inventors: Ling Chen (Darmstadt), Frank Michel (Rosbach v. d. Höhe), Micha Heinz (Darmstadt)
Primary Examiner: Patrick O Neill
Application Number: 15/806,880
International Classification: H03K 5/04 (20060101); H03K 7/06 (20060101); H03K 7/08 (20060101);